1 files changed, 59 insertions, 0 deletions
diff --git a/src/vendor/golang.org/x/net/quic/stateless_reset.go b/src/vendor/golang.org/x/net/quic/stateless_reset.go
new file mode 100644
index 0000000000..8907e2e58b
--- /dev/null
+++ b/src/vendor/golang.org/x/net/quic/stateless_reset.go
@@ -0,0 +1,59 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package quic
+
+import (
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"hash"
+	"sync"
+)
+
+const statelessResetTokenLen = 128 / 8
+
+// A statelessResetToken is a stateless reset token.
+// https://www.rfc-editor.org/rfc/rfc9000#section-10.3
+type statelessResetToken [statelessResetTokenLen]byte
+
+type statelessResetTokenGenerator struct {
+	canReset bool
+
+	// The hash.Hash interface is not concurrency safe,
+	// so we need a mutex here.
+	//
+	// There shouldn't be much contention on stateless reset token generation.
+	// If this proves to be a problem, we could avoid the mutex by using a separate
+	// generator per Conn, or by using a concurrency-safe generator.
+	mu  sync.Mutex
+	mac hash.Hash
+}
+
+func (g *statelessResetTokenGenerator) init(secret [32]byte) {
+	zero := true
+	for _, b := range secret {
+		if b != 0 {
+			zero = false
+			break
+		}
+	}
+	if zero {
+		// Generate tokens using a random secret, but don't send stateless resets.
+		rand.Read(secret[:])
+		g.canReset = false
+	} else {
+		g.canReset = true
+	}
+	g.mac = hmac.New(sha256.New, secret[:])
+}
+
+func (g *statelessResetTokenGenerator) tokenForConnID(cid []byte) (token statelessResetToken) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	defer g.mac.Reset()
+	g.mac.Write(cid)
+	copy(token[:], g.mac.Sum(nil))
+	return token
+}